The invention is directed to electronic circuits for receiving an A.C. signal and for duly rectifying that signal.
Conventional full-wave rectifiers are normally constructed with diodes and arranged, for example, in a so-called "bridge" circuit for developing a fully rectified version of an A.C. input signal. Such rectifiers are frequently used in power supplies for rectifying the A.C. line voltage.
For certain applications, particularly where the signal to be rectified has a small amplitude and it is desirable to develop a rectified but otherwise linear output, diode rectifiers are unsuitable because of their inherent non-linearity. In addition, diode rectifiers require complimentary inputs (two A.C. inputs of the opposite polarity), thus adding to the cost of the system. Moreover, in applications where it is desirable to vary the gain of the rectifier, diode rectifiers are unsuitable because they are incapable of providing that function.
In many applications it is also desirable that the rectifier be capable of fabrication with integrated circuit technology. Temperature stability and repeatable performance characteristics become of paramount importance in such instances. However, diode rectifiers and other conventional rectifiers are generally incapable of completely satisfying all these requirements, particularly where "small signal" rectification is required.
Furthermore, it is advantageous in some applications to utilize a full-wave rectifier capable of receiving either or both polarities of an input signal and providing rectified outputs of either or both polarities. Conventional rectifiers are generally incapable of providing this function without further complicating their structure. Accordingly, prior rectifiers have been, to a large extent, somewhat unsuitable for use in a variety of "small signal" applications.